Electrodeposition of nickel



I 2,782,152 ELECTRODEPOSITION F NICKEL Arthur H. Du Rose, Euclid, andJohn D. Little, Bay Village, Ohio, assignors to The Harshaw ChemicalCompany, Cleveland, Ohio, a corporation of Ohio No Drawing. ApplicationFebruary 16, 1954, Serial No. 410,712

7 Claims. (Cl. 204-49) This invention relates to electrodeposition ofnickel and more specifically to a process for producing electrodepositsof greatly lncreased brightness and smoothness, as taken from theplating solution, without bufling or polishingof United States Patent2,782,152 Patented Feb. 19, 1957 amide, but also one or more of'certainorganic, leveling addition agents of the following class:

- carbon. The central carbon-may carry one OH group increase theirbrightness by the use of addition agents of the type of saccharin ornaphthalene sulfonic acids result in improved brightness with loss ofsmoothness when the surface being coated is quite smooth, and can resultin decrease in both smoothness and brightness when the surface to becoated is quite rough. 'It was found, for example, that when an aqueous,acid solution containing 240 grams per liter of nickel sulfateheptahydrate, 40 grams per liter of nickel chloride hexahydrate and 40grams per liter of boric acid was utilized and coumarin was used inconcentration of 0.25 gram per liter as the sole crease in smoothness isremarkable, and thispr'operty of coumarin has formed the basis of acommercial semibright solution now being widely used. When the attemptwas made to increase the brightness by the addition of agents such assaccharin or naphthalene sulfonicacids, 1

it was found that increased brightness was secured, but at thecost of apart of the smoothing action of the coumarin. For example, it was foundthat when the above described solution was varied by adding 3.5 gramsper liter of naphthalene disulfonic acid an increase in brightness wassecured, but the gain in smoothness over the base metal was only 2.2microinches, the same type of base metal being used. If, instead ofusing naphthalene sulfonic acids, saccharin was used to improve thebrightness, improved brightness was obtained and the gain in asmoothness was about the same. Many other sulfonic acidsand-sulfonamidesshow similar results. Whenthe surface to be coated is not so smooth, e.g. 20't'o-29 R. M. S. as shown by the Brush surface analyzer, the lossof the smoothing action may be so great as to overshadow the tendencytoward increased brightness and actually appear to decrease the lusterof the deposit.

In accordance with the present invention it has now been discovered thata large portion of the lost smoothing action just described can berestored if there is added, in addition to the coumarin, not only anaromatic sulfonand may be connected by a double bond to one of the ringsas in'the dyes.

' As examples may be mentioned,

(a) Triamino triphenyl methanes, (H2NCsH4)aCH (b) Diaminodiphenylmethanes, (HzNCsH4)2CH2 (c) Triaminotolyl phenyl carbitol hydrochloride(d) Triaminotolyl diphenyl methane hydrochloride (reduction product ofFuchsin) (e) Pentamethyl triamino triphenyl methane acetate (reductionproduct of methyl violet) (f) Hexamethyl -p.p'-diaminofuchsonimonium(Crystal Violet).

While these leveling agents do not completely restore the full smoothingaction of coumarin, they .do, in some instances, approach that result,and in other instances restore a large portion of it. p

The preferred acid nickel solution in connection with which theinvention may be realized is an aqueous solution containing nickelsulfate equivalent to from to 400 grams per liter of nickel sulfateheptahydrate, nickel chloride equivalent to from 10 to 75 grams perliter of nickel chloride hexahydrate, and from 10 to 50 grams per liter,preferably 15 to 40 grams per liter, of boric acid or other buffer suchas formic acidforcitric acid. To this fundamental solution there may beadded in accordance with the present invention one or more aromaticsulfonamides to a concentration from /2 gram per liter to saturation,one or more coumarin compounds to a concentration, from.,0.01 to0.5 gramper liter, and one or more leveling agents of the above indicated classin concentrations less than half a gram per liter, for example,from'0.0005 to 0.3 gram per liter. The concentrations .of these.compounds required for best results will be with-. in the rangesindicatedv in the respective tablesv opposite each of said compounds,and very desirably will be'approximately the specific concentration setforth opposite each compound in the tables. H

The compounds listed in Table I are examples of sulfur compounds whichwhen used in connection with coumarin and certain coumarinderivativesproduce an increase in brightness with some loss insmoothness. Numerous other similar compounds produce the same effect invarying degree. They are aromatic sulfonamides and sulfimides. Thecompounds of Table II are examples of coumarin compounds which can beused. -Alkyl and acyl derivatives of-coumarin having 1 to 4 carbonatoms, and the chlorine and carboxy derivatives thereof are suitable.The comchloride pounds effective to increase smoothing power (andbright- 'ness) of coumarin type smoothing agents lost by the addition ofsulfur compounds of the type of those listed in Table I. .Coumarinsulfonic acids are not equivalent to the above indicated coumarincompounds.

Preferably, the solutions are operated in pH range from 2.5 to 4.5, thetemperature is maintained within the range from F. to F., and thecathode current density is maintained within the range from 5 to 100 a.s. f.

Formaldehyde may be used in the above described solutions at aconcentration of from 0.05 to 0.5 gram per liter for the purpose ofretarding or minimizing the effect of breakdown products of coumarin orderivative such as listed in Table II.

Specific examples which have yielded excellent results are indicated inTable IV.

Other basic solutions capable of yielding nickel ions forelectrodeposition may be employed. Preferably there should be present inthe solution at least one nickel salt of the class consisting of nickelsulfate, nickel chloride, nickel fluoborate and nickel sulfamate. Thenickel ion concentration should in any case be within the range whichwould result from the presence of from 100 to 400 grams per liter ofNiSO4.7H2O.

Table I Optimum Preferred Range, Concentra g./l. tion, g./l.

(1) Benzene sullonamide (PhSOQNHE) 0.5 to 3.0 1. (2)p-Toluenesulfonamide (OHgCrHiSOgNHz). 0.5 to 3.0 l. 0 (3) Sacchnrin(o-benzosulfimid) 0.5 to 3.0 1. 0 (4) Dibenzene snlt'onamide (PhSONHSOrPh) and its 1110110- and di-chioro derivatives 0.5 to 5.0 1.0 (5)p-Benzene-bis (N-sulphonylbenzenesnlfonamide(PhS()zNHSOaCeIEIrSOzNHSOzPll). v 0.5 to 6.0 1. 0 (6) N-ethene sulfonylbenzene sulfonamide.. 0.5 to 5.0 l. 0 E7) Monoand di-chlorobenzenesyllonamides. 0.5 to 5.0 1. 0

8) Monoand di-chloro derivatives of (2) and (5) above 0.5 to 5.0 1. 0(9) Bi-dibenzenesulionamide (PllSOzNHSQz- 0.5 to 5.0 1.0CQH4C5H4SOZNHSO2PII 0.5 1.0 5.0 l. 0 (10) Monoand di-chloro derivativesof (9) above 0.5 to 5.0 1.0 (11) Dibenzcne snlfonamide ether (Phi-102-NHSO CALOOglEIrSOnNHSOzPh) 0.5 to 5.0 1. 0

Table II Preferred Range, g./l. Concentration, -I

0. 05 to 0.25 0. l. 0. 05 to 0.25 0. 1 0.05 to 0.25 0. 1 0.05 to 0.250.1 (i-earboxy coumarin 0.05 to 0.25 0.1

Table III Preferred Range, g./l. Concentration, g./l.

(HQNCQHQQCOH 002 to 01 005 (3) Fuchsin dye (HzNC Hi)zC-=C6H NHg .002 to.01 .005 (4) Trlamino tolyl phenyl Cnrbltol hydrochloride .002 to .01.005 (5) 'lrinmino tolyl diphcnyhuethane hydrochloride .002 to .01 .005(0) Pentamethyl triamino trlphenyl methnne acetate .002 to .01 .005 (7)Hexamethyl-p.p'-dlamino iuohsonimonium chloride .002 to .01 .005

Table IV Grams per Liter 300 300 300 300 45 45 45 45 40 40 40 40 0.20.06 1n 0. l 0. 1 0. 1 0. 1 Toluene sulionamide 1.0 Bl-dibenzeuesultonnmlde 1. 0 1. 0 Trlamino-triphenyl methane 0.005 0.0075 0.0050.0075

Having thus described the invention, what is claimed is:

l. A solution for electrodeposition of nickel in the form of bright andsmooth deposits, said solution containing a nickel ion yielding compoundof the class consisting of nickel sulfate, nickel chloride, nickelsulfamate and nickel fluoborate together with cooperating additionagents, one of said addition agents being an organic sulfur compoundcontaining the group one thereof being selected from the classconsisting of conmarin and its alkyl, aeyl, chlorine and carboxyderivatives and a third thereof being an aminopolyaryl methane compoundhaving six nuclear carbon atoms in each aryl group said first mentionedaddition agent being present in concentration from one-half gram perliter to saturation, said second mentioned addition agent being presentin concentration from 0.01 to 0.5 gram per liter and said thirdmentioned addition agent being present in concentration from 0.0005 to0.3 gram per liter.

2. A process for producing bright, smooth electrodeposits of nickelcomprising electrolyzing between an anode and a cathode a solutioncontaining nickel sulfate equivalent to from 100 to 400 grams per literof nickel sulfate heptahydrate, nickel chloride equivalent to from 10 to75 grams per liter of nickel chloride hexahydrate and a group of threecooperating addition agents, one of said addition agents being anorganic sulfur compound containing the group one thereof being selectedfrom the class consisting of coumarin and its alkyl, acyl, chlorine andcarboxy derivatives and a third thereof being an aminopolyaryl methanecompound having six nuclear carbon atoms in each aryl group said firstmentioned addition agent being present in concentration from one-halfgram per liter to saturation, said second mentioned addition agent beingpresent in concentration from 0.01 to 0.5 gram per liter and said thirdmentioned addition agent being present in concentration from 0.0005 to0.3 gram per liter.

3. A process according to claim 2 wherein said solution contains from 10to 50 grams per liter of boric acid.

4. The invention a defined in claim 2 wherein said aminopolyaryl methanecompound is a triaminotolyl diphenyl methane.

5. The invention defined in claim 2 wherein said organic sulfur compoundis bidibenzene sulfonamide,

6. The invention as definedin claim 2 wherein said aminopolyaryl methanecompound is a tniamino tolyl diphenyl methane and said aromatic sulfurcompound is bidibenzene sulfonamide.

7. The invention as defined in claim 2 wherein said third mentionedaddition agent is present in concentration from 0.002 to 0.01 gram perliter.

References Cited in the file of this patent UNITED STATES PATENTS2,198,267 Lind et a1 Apr. 23, 1940 2,635.076 Du Rose Apr. 14, 1953

1. A SOLUTION FOR ELECTRODEPOSITION OF NICKEL IN THE FORM OF BRIGHT ANDSMOOTH DEPOSITS, SAID SOLUTION CONTAINING A NICKEL ION YIELDING COMPOUNDOF THE CLASS CONSISTING OF NICKEL SULFATE, NICKEL CHLORIDE, NICKELSULFAMATE AND NICKEL FLUOBORATE TOGETHER WITH COOPERATING ADDITIONAGENTS, ONE OF SAID ADDITION AGENTS BEING AN ORGANIC SULFUR COMPOUNDCONTAINING THE GROUP